I'm not really sure if you are asking how mIRC works, or where to find games for a channel or ...

Well... if you click on Intro to mIRC or Intro to IRC to the left, you will see some basics. mIRC is an IRC client used to connect to any of a bazillion networks by way of their servers. Diff networks allow you to open your own channel/room, some allow registration others dont. Each network has an AUP (acceptable use policy) which you will find on their websites, and some general info is given when you connect in the server's MOTD (message of the day)
Quite honestly i dont know what all games would be available, altho i know many ppl use trivia bots in their channels. You mite want to check out gamesnet's
web page as they mite be what you have in mind.